Complete Genome Sequences of the Novel Cluster BP Phages Infecting Streptomyces sanglieri, AxeJC, Cumberbatch, Eastland, Eklok, HFrancette, Ignacio, Piccadilly, and Vondra

ABSTRACT The Streptomyces sanglieri bacteriophages AxeJC, Cumberbatch, Eastland, Eklok, HFrancette, Ignacio, Piccadilly, and Vondra form a novel actinobacteriophage cluster, BP. These siphoviruses have circularly permuted genomes with an average size of 37,700 bp and a GC content of 71%. Each genome contains approximately 58 protein-coding genes, with no tRNAs.

These eight phages were isolated using Streptomyces sanglieri UNT16F27A and standard procedures (1). Briefly, nutrient broth inoculated with Streptomyces sanglieri was added to soil samples and allowed to incubate at 30°C for 2 days before the mixture was centrifuged (4,000 Â g), the supernatant was filtered (0.22-mm filter), and the filtrate was spread plated with Streptomyces sanglieri on nutrient agar supplemented with 10 mM MgCl 2 , 8 mM Ca(NO 3 ) 2 , and 0.5% glucose. Plaques were purified by three rounds of plating, resulting in uniform circular plaques that ranged from 0.5 to 1.5 mm in diameter. Negative-staining transmission electron microscopy revealed all phages to be siphoviruses, with a capsid diameter and a tail length of approximately 60 and 190 nm, respectively (Fig. 1).
DNA was extracted using the Promega Wizard DNA cleanup system. Sequencing libraries were constructed using the NEBNext Ultra II DNA library preparation kit and sequenced using an Illumina MiSeq system (v3 reagents), generating 150-base single-end reads. All reads were assembled into single contigs as described by Russell (2) using Newbler v2.9 (3) and Consed v29 (4). Sequencing results and genome characteristics are listed in Table 1. All isolates contain circularly permuted genome ends, as determined by even distribution of reads across the assembly, with an average length of about 37,700 bp and GC contents above 71%. Based on shared GCS exceeding 85%, as assessed using the GCS tool at the Actinobacteriophage Database (https://phagesdb.org), these phages are grouped together to form a new actinobacteriophage phage cluster, BP (5, 6).
The genes are highly conserved in all eight phages, although Vondra contains two small clusters of genes for which there are no homologues in the Actinobacteriophage Database. Each phage contains a predicted serine integrase gene, which suggests that these phages are temperate. The integrase of cluster BP phages was most similar to those of phages in cluster BC. The putative endolysin genes are highly conserved in all eight phages (89 to 100% protein similarity) and share similarity with endolysins found in members of 10 other Streptomyces phage clusters.
Data availability. The GenBank and SRA accession numbers are listed in Table 1.

ACKNOWLEDGMENTS
We thank Daniel Russell and Rebecca Garlena for sequencing and assembling the genomes at the University of Pittsburgh and for reviewing those sequenced at the University of North Texas, Tracy Kim and Taegun Kwon for sequencing the samples at the University of North Texas, and the Science Education Alliance-Phage Hunters Advancing Genomics and Evolutionary Science (SEA-PHAGES) program for support.